Foam inhibition of oil



atent FOAM INHIBITION OF OIL John P. McDermott, Springfield, and MalcolmF. Hurley,

Elizabeth, N. J., assignor to Esso Research and Engineermg Company, acorporation of Delaware No Drawing. Application August 1, 1951, SerialNo. 239,851

3 Claims. (Cl. 252-325) The present invention relates to the foaminhibition of oils and particularly to the prevention of foaming andfrothing in organic compositions such as hydrocarbon oils and relatedmaterials which contain additives tending normally to promote foaming.The invention is applicable particularly to lubricating oils containingdetergent additives and the like but it is applicable also to otherliquid hydrocarbon oils having a viscosity ranging between that ofkerosene up to very heavy viscosities which are characteristic of themost viscous lubricating oils.

As is well known in the prior art, lubricating oils, hydraulic oils andthe like which foam excessively frequently cause operating difiicultiesin machinery as well as in the processing of the oils themselves.Various materials have been proposed in the past for adding to such oilsto inhibit their foaming. In recent years there has been a marked trendtoward the use of detergent additives, particularly in lubricating oilsand hydraulic oils, and, to a lessor extent, in fuel oils. Theseadditive materials, which are desirable because they prevent sludging,deposition of gum and the like, are strong foam promoters and the moderntendency to use such materials in increasing quantities gives rise toincreasing difiiculties with foaming.

It has been proposed in the past to inhibit foaming of organiccompositions by adding minor proportions of various materials includingfluorinated hydrocarbons, long chain alcohols, and small quantities ofsilicone polymers having foam suppressing characteristics in oils. Theaction of these anti-foamants appears to be quite specific and theiractivity cannot, in general, be predicted. Anti-foaming activity appearsto have some relation to oil-insolubility as well as to surface tensionbut the factors which determine whether a given oil composition willfoam are not clearly understood.

In general, the heavier the hydrocarbon oil and the greater its contentof detergent additive, the greater will be its tendency to foam and themore difficult to inhibit its foaming. The foaming tendency, however,varies also with the particular type of oil and varies even more withthe particular type of detergent, or other foam promoting additive. Thefatty acid soaps of most metals, the oil soluble sulfonates, variousaliphatic esters and amines and the salts of alkylated aromaticcompounds such as alkyl phenol sulfides, alkyl phenolates, thephosphorus sulfide treated derivatives of such materials and the like,frequently tend to promote foaming in conventional mineral basehydrocarbon oils. The degree of foaming in each case varies with theparticular constituents and the type and degree of agitation to whichthe oil is subjected.

In general, prior art attempts to prevent foaming of oils have beenbased upon the addition of certain antifoaming materials to the oilcompositions. One feature of the present invention resides in thediscovery that a pretreatment of the foam promoting additive itself,before addition to the oil, can greatly reduce the foaming tendency ofoil containing the additive.

According to the present invention, foam promoting additive of thegeneral type mentioned above, may be treated in a very simple andinexpensive manner to reduce greatly their tendencies to foam uponagitation of oil compositions containing them. The treatment consists intreating such additives with an aliphatic ketone containing from about 3to about 7 carbon atoms. The treatment is rather specific and higherketones are not useful. Thus acetone, methyl-ethyl ketone, methyl-propylketone, diethyl ketone, ethyl-propyl ketone, mesityl oxide((CH3)2C=CHCOCH3), diisopropyl ketone methylbutyl ketone, and ethylbutyl ketone are all useful. The unsaturated ketone, mesityl oxide, isparticularly effective with such materials as the alkaline earth metalsalts of alkyl phenol sulfides and their phosphorus sulfide treatedderivatives but the other ketones mentioned are quite effective also.The ketones of the normal as Well as the isoalkyl type may be used.

The quantity of ketone used should be between 0.1% and 25% of the weightof the additive or detergent material per se. Proportions in the rangeof about 3 to 20% are preferred, especially around 10%.

.A number of experiments were conducted to show the effect of treatingdetergent additives of various types which detergents were added tomineral lubricating oils of SAE 30 grade in concentrations of 5% for thefoaming test.

In general the additive and the ketone treating agent were stirredtogether and heated at a moderately elevated temperature within therange of about to 170 C., with continued rapid stirring, accompanied byblowing with nitrogen. The treating temperature depends of course bothupon the material treated and the treating agent used. With acetone thetreating temperature in the neighborhood of 80 C. appears to bedesirable for phenol sulfide type detergents. For methylethyl ketone,the treating temperature for such detergents should be about C., andabout 120 C., for methyl propyl ketone. For mesityl oxide the treatingtemperatures used in the examples below were around 160 C., and fordi-isopropyl ketone about 170 C. The results of these treatments, asindicated in standard foaming tests (ASTM Foam Test D892-64T) areindicated in the following table. In this Table, the detergent A was abarium salt of di-isobutyl phenol sulfide. Detergent B was a similarsalt, treated however with P285 to improve its performance in certaintypes of mineral lubricating oil, combined with oil soluble calciumpetroleum sulfonate. Detergent C was an alkaline barium alkyl phenolsulfide in combination with oil soluble calcium petroleum sulfonate.

Table I.Efiect of ketone treatment of additives on foaming BLENDS IN SAE30 OIL ASTM Foam Test D892-46T Wt. Deter- Per- Ketone Treat- 75 F. 200F. 75 F. (After gent cent ment 200 F.)

Fl. FS FT li FI FS A 5 None l. 600 500 650 0 595 485 A 5 Mesityl Oxide,370 290 230 0 345 270 10 B 5 Non? 430 425 0 495 430 B 5 Methyl Ethyl 2300 25 0 0 fietone, B s Acetone,10% 300 0 25 o o B 5 Diisopropyl 20 0 40 015 0 Ketone, 10%. O 5 None 470 410 230 0 465 400 C 5 Methyl Ethyl 0 30 0180 0 Ketone, 10%. G 5 Acetone, 10%. 0 40 0 170 0 O 5 Methyl 10 0 30 010 0 Propyl Ketone, 10%. O 5 Mesityl 0x- 15 0 35 0 15 0 lde, 5%. O 5Mesityl 0x- 20 0 30 0 20 0 ide, 1%.

Table I.--Continued BLENDS IN SAE 50 OIL 1 Foaming tendency. Z Foamstability.

It will be understood that the oil compositions which are subjected tothe treatments described above form newand useful products, and that thetreatments are applicable to fuel oils, hydraulic oils, diesel fuels,gear lubricants, crank case lubricants, and various greases and types ofhydrocarbon oil compositions having a viscosity at least as great asthat of kerosene. The oil compositions may incorporate various otherconventional additives such as anti-oxidants, pour point depressants,corrosion inhibitors, detergents, film strengthening agents,anti-friction agents, extreme pressure agents, anti-rust agents, and thelike as will be apparent to those skilled in the art. While referencehas been made in general to the hydrocarbon, or mineral base oils, theinvention is applicable also to other organic oils consisting of, orcontaining synthetic oils such as polyesters, polyglycols,polyglycol-ethers and the like so far as the same problems of foamingand foam inhibition are encountered therein.

What is claimed is:

1. The product of the treatment of an oil-soluble foampromotingdetergent selected from the group consisting of the alkaline earth metalsalts of alkyl phenol sulfides, the phospho-sulfurized derivatives ofsaid salts and mixtures of said salts, with 0.125% of its weight ofmesityl oxide at a moderately elevated temperature in the neighborhoodof about 160 C. while stirring, said product having a reduced tendencyto promote foaming.

2. The process of substantially reducing the tendency of detergentadditives to promote the foaming of organic oil compositions containingthe same, which comprises stirring and heating an additive selected fromthe group consisting of the alkaline earth metal salts of alkyl phenolsulfides, the phospho-sulfurizcd derivatives of said salts, and mixturesof said salts, prior to incorporation in said oils together with 01-25%by Weight, based on the additive, of mesityl oxide at a moderatelyelevated temperature in the neighborhood of about 160 C.

3. An oil composition of reduced foaming tendencies comprising a majorproportion of an organic oil composition of viscosity at least as highas kerosene and a minor detergency-improving proportion of about 5% byweight of a normally foam-promoting detergent additive selected from thegroup consisting of the alkaline earth metal salts of alkyl phenolsulfides, the phospho-sulfurized derivatives of said salts, and mixturesof said salts, which has been stirred and heated prior to incorporationin said oil, together with about 01-25% by Weight, based on theadditive, of mesityl oxide at a moderately elevated temperature in theneighborhood of about 160 C.

References Cited in the file of this patent UNITED STATES PATENTS2,430,858 Borsoif et a1. Nov. 18, 1947

3. AN OIL COMPOSITION OF REDUCED FOAMING TENDENCIES COMPRISING A MAJORPROPORTION OF AN ORGANIC OIL COMPOSITION OF VISCOSITY AT LEAST AS HIGHAS KEROSENE AND A MINOR DETERGENCY-IMPROVING PROPORTION OF ABOUT 5% BYWEIGHT OF A NORMALLY FOAM-PROMOTING DETERGENT ADDITIVE SELECTED FROM THEGROUP CONSISTING OF THE ALKALINE EARTH METAL SALTS OF ALKYL PHENOLSULFIDES, THE PHOSPHO-SULFURIZED DERIVATIVES OF SAID SALTS, AND MIXTURESOF SAID SALTS, WHICH HAS BEEN STIRRED AND HEATED PRIOR TO INCORPORATIONIN SAID OIL, TOGETHER WITH ABOUT 0.1-25% BY WEIGHT, BASED ON THEADDITIVE, OF MESITYL OXIDE AT A MODERATELY ELEVATED TEMPERATURE IN THENEIGHBORHOOD OF ABOUT 160*C.